The present invention relates to vapor detection associated with a fuel dispenser, and more particularly to vapor detection in the electronics cabinet portion of the fuel dispenser.
Fuel dispensers, whether gasoline, natural gas, propane, or the like, are getting more complex with time. As a result, increasingly complex electronic circuits are required. As with any electrical component, there is always a chance, albeit slim, of sparking from the electronic circuits. Sparks and fuel vapors may cause a hazardous condition, such as an explosion. To address the potential for this problem, most, if not all, fuel dispenser manufacturers separate the interior of the fuel dispenser into two chambers.
A first hazardous area chamber comprises fuel-handling devices, such as flow meters, pumps, valves, and the like. Fuel dispenser chambers are required to comply with Class 1, Division 1 rules specifying that the electrical connections must use explosion-proof connections and/or terminal boxes. The National Electric Code Handbook, Section 514, details one set of regulatory requirements that are in place for such devices.
A second chamber, typically above the Class 1, Division 1 area, contains the main electronic components of the fuel dispenser, such as payment acceptors, remote communication devices, display circuits, keypad circuitry, and the like. A vapor barrier is frequently positioned between the two chambers to prevent vapor from passing from the fuel-handing hazardous chamber to the electronics chamber. A potted conduit may be used to prevent vapors from contaminating the electronics chamber. Further information about vapor barriers may also be found in U.S. Pat. No. 4,986,445, which is hereby incorporated by reference. Wiring and fuel delivery conduits that extend through the vapor barrier typically have seals therearound to keep the vapor barrier intact.
Typical seals comprise potting solutions, rubber seals, and the like, which may deteriorate over time, may be improperly installed, or otherwise fail, allowing for the potential of hydrocarbon vapors to pass into the electronics chamber and potentially increase the risk of sparks igniting the vapor. Thus, the need for additional safety measures to reduce the risk associated with vapor entering the electronics chamber of the fuel dispenser continues.
The present invention addresses these safety concerns by placing a vapor sensor within the electronics chamber of the fuel dispenser. If the vapor sensor detects the presence of hydrocarbon vapors, or alternatively, changes in the amount of oxygen vapor indicative of hydrocarbon vapor presence, power is decoupled from the electronic components of the fuel dispenser, thus reducing the likelihood of sparking that could cause vapors to combust, ignite, or explode.
Alternate embodiments comprise using a plurality of sensors and/or keeping a log of sensor readings to verify functionality, deviations from calibrations, and the like.